This invention relates to rock and ore crushers, and more particularly to crushers of the vertical shaft impactor type which are arrange to direct rock and ore material onto a rapidly rotating impeller structure that expels the material outwardly at high speed for shattering impact of the expelled rock and ore material within the crusher into smaller fragments and fines which are discharged from the crusher as desired, crushed product.
Next to food, clothing, and shelter, rock in useable form is the most important product of advanced society. It is essential for building homes, roads, buildings, dams, airports, railroads, and other uses for human benefits. Rock in gravel form where deposited is less costly to process than quarry rock, but in either form it rarely can it be used as found, consequently it must be reduced to required sizes; in some third world countries rock is manually crushed with hammers where one person might produce a ton of rock per day of rock in sizes mostly too large for best usage. In modern societies rock is crushed in enormous volumes by machinery and few workers. Rock crushers are normally used in three or more sequential stages: First a compression type primaries either jaw or gyratory for large size rock, second stage usually gyrating cone type for reducing oversize rock from the first stage to the larger useable sizes, and tertiary stage for the smallest but very essential sizes. It is very difficult to produce fine crushed rock with compression type crushers; the stresses are very high and volume is low and the wear rate of wear liners is costly.
Since the mid twentieth century a form of crusher called a “VSI” in the trade, an acronym for Vertical Shaft Impactor, was invented; it uses a high speed impeller mounted on the top end of a vertical shaft. It throws the rock against metal anvils. Many different manufacturers have brought this concept to market, but the extremely high costs of maintenance both in parts and frequent need of labor to change impeller slingers and anvils has been a bane to their success. There is another design of VSI that crushes rock on rock which eliminates anvils and their high costs, but it has less crushing efficiency and higher power demand per ton of net product; it uses essentially the same mechanics as does the anvil design except the rock chamber. The design in this patent application is a new concept of the mechanics of rock on rock crushing; it is substantially easier and faster to service and reduces the costs of fine crushing to be very acceptable.